"There have been some big names go, which is unfortunate, but [it] speaks to the adage that MPs generally measure three things when an election looms. Getting elected, getting into government, getting into cabinet," a veteran Liberal wrote in an e-mail.

"Dion has made the calculation easy."

I'm not sure exactly how many Liberals have now announced they won''t be running again, but I estimate the number to be around 15-20% of the Liberal caucus. That's a huge blow to Dion's leadership and doesn't bode well for the Official Opposition.